reflect_tools 0.9.0

Collection of mechanisms for reflection.
Documentation
# Docs

### Scope

- **Purpose**: Provide structured design documentation for the `reflect_tools` crate.
- **Responsibility**: Contains all doc entity types for entity reflection and fields iteration subsystems.
- **In Scope**: Design decisions, API contracts, correctness invariants, data structure descriptions.
- **Out of Scope**: Source code comments (→ `src/`); test documentation (→ `tests/readme.md`); user onboarding (→ `readme.md`).

### Responsibility Table

| File | Responsibility |
|------|----------------|
| [entities.md]entities.md | Cross-entity index of all doc types and instances |
| [doc_graph.yml]doc_graph.yml | Machine-readable cross-reference graph |
| [api/]api/readme.md | Public interface contracts for reflection and fields APIs |
| [data_structure/]data_structure/readme.md | In-memory data type descriptions |
| [feature/]feature/readme.md | Navigational hubs for major subsystem features |
| [invariant/]invariant/readme.md | Correctness properties and enforcement mechanisms |